#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <sys/types.h>
#include <sys/wait.h>
#include <string>
#include <unistd.h>
#include <string.h>

#define N 2
#define NUM 1024

using namespace std;

//child
void Writer(int wfd)
{
  string s="hello, I am child";
  pid_t self=getpid();
  int number=0;

  char buffer[NUM];
  while(true)
  {
    buffer[0]=0;
    snprintf(buffer,sizeof(buffer),"%s-%d-%d",s.c_str(),self,number);
    // cout << buffer << endl;
    // 写入父进程
    write(wfd,buffer,strlen(buffer));
    sleep(1);
  }
}

//father
void Reader(int rfd)
{
    char buffer[NUM];

    while(true)
    {
        buffer[0]=0;
        size_t n =read(rfd,buffer,sizeof(buffer));
        if(n>0)
        {
            buffer[n]=0;
            cout << "father get a message[" << getpid() << "]#" << buffer << endl;
        }
    }
}

int main()
{
    int pipefd[N]={0};
    int n=pipe(pipefd);
    if(n<0)return 1;
    // cout << "pipefd[0]: " << " ,pipefd[1]:" << pipefd[1] << endl;
    
    // child -> w,father -> r
    pid_t id=fork();
    if(id<0)return 2;
    if(id == 0)
    {
        // child
        close(pipefd[0]);
        //IPC code
        Writer(pipefd[1]);

        close(pipefd[1]);
        exit(0);
    }
    //father
    close(pipefd[1]);
    //IPC code
    Reader(pipefd[0]);

    pid_t rid=waitpid(id,nullptr,0);
    if(rid<0) return 3;
    close(pipefd[0]);
    return 0;
}